The finishing touches

The fashion for putting a transparent opening in the back of a watch is a relatively recent trend, but a pleasing one. While in the old days mechanisms were hidden from sight – in any case, the sapphire crystal didn’t exist that can now provide as strong a casing as steel – watch houses have recently woken up to the fact that a visible movement holds its own allure. As a result, the intricate arts of movement finishing, developed in the days of prestige pocket watches, are being taken to new heights.

The Geneva Seal – a strict quality standard for the highest-grade watches – has 12 technical criteria that mark a locally-produced watch as a true specimen of Genevoise haute horlogerie. And as many as five of these relate to how the watch’s movement is finished.

Many of these decorative calling cards are now industry standards: steel parts with polished edges, drawn-out flanks, smoothed visible parts, polished or circular-grained screw heads; mirror-polished jewels with polished sinks; interlocking cogs chamfered above and below with polished teeth; polished pivots and pinions. All of which combines to spectacular effect when viewed from the back. Or even from the front; the woven strands of Montblanc’s Villeret 1958 tourbillon bridge, for example, takes one man 40 hours to polish, but the resulting, dazzling gleam makes all the difference.

It may seem superficial, but in today’s era of automated manufacture, finissage has become more important than ever in imparting value to a watch. The higher up the prestige ranks you go, the more handiwork will have gone into a movement’s finishing – it may account for more than a third of a watch’s final cost. With even the most revered houses employing computer-controlled electroerosion and multi-axis milling to create the majority of their components, exceptional hand finishing using pastes, abrasives, wooden files and superhuman diligence is now essential to maintain their reputation for handcraftsmanship.

As it happens, such working has sensible technical origins. A degree if finish is understandably necessary to the snug fit and smooth running of the wheels, pinions and cams, while in the days before tightly sealed cases, applying a textured pattern such as Côtes de Genève striping to flat surfaces ensured that invading dust didn’t slide easily into the bearings and clog things up. But nearly all varieties of polish are purely cosmetic; beauty for beauty’s sake, and for the sake of the sheer labour involved.

The question is, with automation becoming better and more widely accepted, would the traditions of hand finishing continue if the artist’s subtlety of touch could be replaced by a machine? It’s difficult to be sure, but for now at least the finisher’s future is safe, as there are still polishing techniques that a machine cannot replicate: step forward the notoriously tricksy intersection of two acute-angled edges or the evenly contoured serpentine edge, as seen on the main gearwheel sitting proud of a Patek Philippe minute repeater tourbillon.

But most importantly, a machine is not a human. These watches are personalised by artists, and thereby endowed with tremendous emotional value before you’ve even worn it, let alone passed it onto your son. That’s as integral a quality as any to an haute horlogerie watch.

1 Bevelling / chamfering
A particularly meticulous finish that highlights the rim of watch parts by eliminating the edge between the surface and the flanks with a wooden grinding wheel and diamond paste. Angles are where the true skill of the beveller can be judged, so high-end watch components feature more angles than are strictly necessary. It takes seven days to bring the bridges of Girard Perregaux’s Three Gold Bridges to a flawless gleam, keeping the chamfer width constant and its edges parallel.

2 Côtes de Genève
Perfectly parallel Geneva waves – named after the waves lapping on the shores of Lake Geneva, and often applied manually with rotating boxwood pads covered with abrasive paste – are the most common form of finish. Like a freshly mowed lawn, they form a satisfying pattern of alternating light and dark stripes, lending coherence to disparate bridges when aligned precisely.

3 Snailing
Rather like a hurricane viewed from above, snail polishing can be spotted as a shimmering vortex, usually decorating a flat circular surface like a winding barrel.

4 Perlage
A dimpled pattern of overlapping circles, which is applied by dabbing a spinning rubber tip onto flat metal surfaces.

5 Black polishing
A technique that takes years to master, black polish is so-called for its extreme level of shine – either bright white or jet black, depending on how you angle the of the component. The result should be totally scratch-free, even under magnification.